An Optical Serrodyne Frequency Translator
At present there is a considerable interest in the use of optical fibres as sensors and transducers. In these devices a long length of fibre is used to convert a small-velocity perturbation due to some external influence into a measurable phase shift. A number of schemes has been proposed for measuring this phase, generally using some form of interferometer. Some schemes employ heterodyne techniques to translate the phase change to a convenient intermediate frequency; this offers a number of advantages, including greater sensitivity and the prospect of a digital output.